Someone must love you, since there was a shiny new Mac waiting under the tree for you this morning. I know you're excited to get it up and running, and it'll be easier than you think. There are some tips I would like to share with you, oh newly inducted acolyte to the Cult of Mac, that should make your Mac adventure even more fun.
Toss aside the included mouse: All desktop Macs now come with the Mighty Mouse (except the Mac mini, of course), which is a multibutton mouse that pretends to be a one button mouse. Toss it aside and get yourself a real mouse (the Logitech MX Revolution Wireless Laser Mouse is currently my favorite mouse of all time). If you received a portable Mac you should also pick yourself up a mouse. The included Trackpad is nice, but a mouse is much nicer.
Download Quicksilver and Growl: You might not get why Quicksilver and Growl are awesome. You might not get it for awhile, but when it clicks your Mac experience will become even better. Trust me, would a blogger lie to you?
Enable Tabbed Browsing in Safari: Launch Safari, go to 'Preferences,' 'Tabs,' and check the 'Enable Tabbed Browsing.' You might also want to check out many of the Mac only variants of web browsers: Omniweb, Optimized Firefox, Camino (which is still my personal favorite), and Shiira.
Drag your Applications folder to the Dock: I wrote a post, about a year ago, detailing how to move your hard disk into the Dock for easy access. I have since amended my setup to include only the Applications Folder in the Dock, since that is where I needed to go most of the time anyway. Follow the instructions in my previous post, but just drag the Applications Folder in the Dock instead of the entire hard disk.
Charge the battery, but not too much: If you found a MacBook or MacBook Pro under the tree make sure that you plug it in the first time you use it. Apple has a list of tips for maximizing the battery life of portables, give it a read to ensure many happy cycles on your battery.
Read TUAW: I admit that I am a little biased, but we here at TUAW strive to be that Mac geek friend of yours that knows where to find all the cool Mac stuff on the web. Our knowledgeable bloggers (and me!) are always ready with new tips, tricks, and news to share so make sure you come back often.